For fermented cime di rapa, combine salt and 2 litres water in a non-reactive container, add cime di rapa and soak for 1 hour. Squeeze excess liquid from cime di rapa, transfer to a bowl with remaining ingredients, mix thoroughly, squeezing and pressing with your hands to create a wet mix, then add salt to taste. Transfer to a clean non-reactive container to fit snugly and press to remove air pockets. Weight down with a lid that fits perfectly inside container to cover and compress mixture. Cover with muslin and set aside in a warm place for 3 days to ferment. When fermented, drain, finely chop, and refrigerate in an airtight container until required. Makes about 1 cup. Fermented cime di rapa will keep refrigerated for 2 months.